Scientists keeping count of mayflies
Molly Kavanaugh Plain Dealer Reporter
- Think of mayflies as lost children who return home.
After the celebration, the tough questions get asked:
How can we keep better track of them? What are the signs
they might disappear again? How does this affect the lives
of those around them?
About two dozen scientists from Ohio, Michigan,
Pennsylvania and Windsor, Ontario, met Friday and
yesterday to discuss this winged, nonbiting insect in
which they share an interest. The two-day gathering took
place at Heidelberg College, where mayfly studies funded
by the Lake Erie Protection Fund are being conducted.
"We don't just have a passing interest in what this
group is doing. It's going to be very critical in the
way agencies manage the environment," said Roger
Thoma, Lake Erie biologist with the Ohio Environmental
Mayflies, prominent along the lake for years, disappeared
from the polluted waters of Lake Erie in 1953 - scientists
call it "the crash" - and did not return for
40 years. By 1996, the western basin was full of the flies,
which have an unusual life cycle on water and an annoying
one on land.
The flies spend about two years as nymphs in the lake
sediment, then emerge, usually in June and July. For 24
hours, they molt, mate and die, leaving behind a fishy
odor and bodies that litter streets and sidewalks.
In Port Clinton, truckloads of dead insects have to be
hauled to the dump. The insects have shorted out power
plants in Toledo and Monroe, Mich.
Counting mayflies is tricky business, and speakers Friday
shared some of their techniques. Canadian scientists head
to harbors, put down a white sheet, cover it with a Hula
Hoop and wait for nightfall. Then they count how many
mayflies end up inside the ring. Along the Ohio shoreline,
lakefront residents volunteer to count mayflies on their
Tracking the nymphs requires different tactics.
In Pennsylvania, researchers scuba dive and scoop up
sediment. Ohioans drop a clawlike container over the side
of the boat, gather mud and haul it in.
The month, time of day and frequency of visits also vary
"One of the goals is to reach consensus on methods,"
said Kenneth Krieger, a senior research scientist at Heidelberg
College and director of the college's mayfly studies.
While mayflies are a tasty diet for fish and aren't considered
harmful to the lake, some scientists are taking a closer
look. Since the nymphs spend a couple of years squirming
around in the sediment, there is concern that they might
be releasing contaminants into the water.